Design and investigation of a modular focused collimator based multiple detector ring system for SPECT imaging of the brain

The ability of focused collimators to achieve both high sensitivity and high resolution at depth makes them highly desirable for SPECT imaging. Tomographic systems with stationary detector rings are known to have the advantages of simplicity, stability and tolerance to variations in detector response. We have combined these two desirable features in the design of a multidetector ring SPECT system with a unique modular focused collimator for brain imaging. In a manner similar to that employed by 4th generation CT scanners, each detector unit acquires a set of fan beam projection data while the collimator assembly makes a complete rotation. Our investigation shows that the new tomograph can be expected to achieve a spatial resolution of 8 mm and a system sensitivity of 2, 500 cps/μCi/cc for a 13 mm thick image slice. The high performance characteristics of the new SPECT system should make it a useful tool in functional imaging of the brain, especially in perfusion studies using the current I-123 or Tc-99m labeled agents.